First principles calculations of the electronic structure and optical properties of (001), (011) and (111) Ga0.5Al0.5As surfaces

Yu, Xiaohua; Ge, Zhonghao; Chang, Benkang; Wang, Meishan

doi:10.1016/j.mssp.2013.07.007

Cited by 11 publications

(2 citation statements)

References 25 publications

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“…As depicted in Table 2, the work functions of different surface models before and after adsorption are calculated and analyzed. The calculated work function of the clean Al 0.5 Ga 0.5 As (001) surface and Al 0.25 Ga 0.75 N (0001) surface is 4.74 eV and 4.18 eV, which is consistent well with the experimental value 4.85 eV and 4.225 eV in Refs [16,26]. Table 2 shows that the work function value of two surfaces lowered remarkably after Cs adsorption.…”

Section: ) Work Function and Surface Dipole Momentsupporting

confidence: 83%

Comparative Research on Cs Activation Mechanism for Al0.5Ga0.5As (001) and Al0.25Ga0.75N (0001) Surface

Shen

Chen

et al. 2015

IEEE Sensors J.

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To investigate and distinguish the difference of Cs activation mechanism on Al 0.5 Ga 0.5 As (001) and Al 0.25 Ga 0.75 N (0001) surface, plane wave with ultrasoft pseudopotential method based on first-principle density functional theory (DFT) is used. Surface adsorption energy, work function and surface dipole moments with different Cs coverage are calculated and compared. Eight possible Cs adsorption sites are chosen for the Al 0.5 Ga 0.5 As (001) surface while seven high-symmetry sites are considered in the calculation model of Al 0.25 Ga 0.75 N (0001) surface. Results show that when only one Cs atom adsorbed on two surfaces, the adsorption energies are all negative and the adsorption sites are all stable sites. The lowest work function and the most stable adsorption sites with different Cs coverage are obtained and discussed. When different amounts of Cs atoms adsorbed on two surfaces, the work function values of Al 0.25 Ga 0.75 N (0001) surface are all smaller than that of Al 0.5 Ga 0.5 As (001) surface. The work function of Al 0.5 Ga 0.5 As (001) surface decreases with the increase of Cs coverage when the Cs coverage changes from 0 monolayer (ML) to 0.75 ML, while Al 0.25 Ga 0.75 N (0001) surface achieves the smallest work function when the Cs coverage is 0.5 ML. Finally, photocurrent curves during Cs activation are recorded. The photocurrent of AlGaAs sample reaches at a peak at the time of 29 min when the Cs coverage rise at 0.75 ML, while the photocurrent of AlGaN sample achieves a peak at the time of 30 min when the Cs coverage rise at 0.5 ML, which is in well consistent with our calculation results.

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Section: ) Work Function and Surface Dipole Momentsupporting

confidence: 83%

Comparative Research on Cs Activation Mechanism for Al0.5Ga0.5As (001) and Al0.25Ga0.75N (0001) Surface

Shen

Chen

et al. 2015

IEEE Sensors J.

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“…Therefore, the diffusion process of photoelectrons will obviously exhibit the relaxation phenomenon. According to Spicer's three-step model [45], the photoemission process of the In0.15Ga0.85As photocathode can be well described. In order to intuitively describe the electron transport process, the energy band structure diagram of the proposed In0.15Ga0.85As photocathode is portrayed in Figure 7.…”

Section: Calculation Methods For Photoemission Performance Of the In ...mentioning

confidence: 99%

Theoretical Study on the Photoemission Performance of a Transmission Mode In0.15Ga0.85As Photocathode in the Near-Infrared Region

et al. 2023

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Benefiting from a high quantum efficiency, low thermal emittance, and large absorption coefficient, InxGa1−xAs is an excellent group III–V compound for negative electron affinity (NEA) photocathodes. As the emission layer, InxGa1−xAs, where x = 0.15, has the optimal performance for detection in the near-infrared (NIR) region. Herein, an NEA In0.15Ga0.85As photocathode with Al0.63Ga0.37As as the buffer layer is designed in the form of a transmission mode module. The electronic band structures and optical properties of In0.15Ga0.85As and Al0.63Ga0.37As are calculated based on density functional theory. The time response characteristics of the In0.15Ga0.85As photocathode have been fully investigated by changing the photoelectron diffusion coefficient, the interface recombination velocity, and the thickness of the emission layer. Our results demonstrate that the response time of the In0.15Ga0.85As photocathode can be reduced to 6.1 ps with an incident wavelength of 1064 nm. The quantum efficiency of the In0.15Ga0.85As photocathode is simulated by taking into account multilayer optical thin film theory. The results indicate that a high quantum efficiency can be obtained by parameter optimization of the emission layer. This paper provides significant theoretical support for the applications of semiconductor photocathodes in the near-infrared region, especially for the study of ultrafast responses in the photoemission process.

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Geometric and electronic structure of Cs adsorbed Ga0.5Al0.5As (001) and (011) surfaces: a first principles research

Chang

Wang

et al. 2014

J Mater Sci: Mater Electron

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First principles calculations of the electronic structure and optical properties of (001), (011) and (111) Ga0.5Al0.5As surfaces

Cited by 11 publications

References 25 publications

Comparative Research on Cs Activation Mechanism for Al<sub>0.5</sub>Ga<sub>0.5</sub>As (001) and Al<sub>0.25</sub>Ga<sub>0.75</sub>N (0001) Surface

Comparative Research on Cs Activation Mechanism for Al<sub>0.5</sub>Ga<sub>0.5</sub>As (001) and Al<sub>0.25</sub>Ga<sub>0.75</sub>N (0001) Surface

Theoretical Study on the Photoemission Performance of a Transmission Mode In0.15Ga0.85As Photocathode in the Near-Infrared Region

Geometric and electronic structure of Cs adsorbed Ga0.5Al0.5As (001) and (011) surfaces: a first principles research

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